The present invention relates to a process for eliminating dust from fiber material guided over a sieve-like surface, and an apparatus for carrying out the process. The fiber material is exposed to a suction airstream guided through the sieve-like surface.
From the taker-in of a card, it is known to guide fiber material during its transport over a sieve-like surface surrounding the taker-in cylinder (see, for example, German Offenlegungsschrift No. 1,510,337). During the time when this fiber material is held in the effective range of the taker-in cylinder, it is further exposed to a suction airstream directed radially outwards. Dust resting loosely on the outside of the fiber material located in the clothing of the taker-in cylinder is thereby sucked off. However, there is the danger that remains of fiber, e.g., husk particles, etc. will stick to the sieve-like surface and clog it.
Fiber material is also guided according to known systems over sieve-like surfaces during dust removal in a blow room (see, for example German Patent Specification No. 3,304,571). Since the suction airstream acts transversely relative to the fiber transport direction, there is again the danger that remains of fiber, e.g., husk particles, etc., will cause clogging of the sieve-like surface.
There is also known a proposal to retain, in the form of a fiber tuft, the sliver fed to an opening cylinder of an open-end spinning apparatus while it is guided over the sieve-like surface surrounding the opening cylinder (see, for example, German Auslegeschrift No. 2,648,715). The advantage of this in comparison with cleaning in the region of the taker-in cylinder of a card is that highly intensive removal of the dust is achieved, since a sliver fed in is opened into individual fibers at this location. However, since the fiber tuft is still retained, as described above, the dust located between the fibers is scraped off by the clothing of the rotating opening cylinder. The dust removed from the fibers in this way is conveyed away by means of the suction air. Even in this known apparatus there is the danger that fiber remains, particles of dirt or the like will stick to the sieve-like surface and thereby reduce the efficiency of dust elimination.
One object of the present invention is, therefore, to provide a process and an apparatus for eliminating dust from fiber material, especially on open-end spinning machines, so that this danger of clogging the sieve-like surface does not exist or at least is considerably reduced (i.e., effectively eliminated if not literally so).
According to one aspect of this invention, a suction airstream, to which fiber material is exposed in the region of the sieve-like surface, is guided away from the fiber material at an acute angle in a sense opposite to the fiber transport direction. Because of the suction airstream orientation having a movement component directed opposite to the fiber transport direction, fly, fiber remains, husk particles, nips, etc., are prevented from becoming stuck in the sieve-like surface. Because of inertia, the fibers and dirt particles instead maintain their previous direction of flight along the wall containing the sieve-like surface. Only micro-dust particles, which because of their low mass are practically free of inertia and can therefore accomplish an immediate change in direction, follow the guided suction airstream through the sieve-like surface.
Particularly intensive cleaning is possible if fiber material is held in the range of influence of a clothing cylinder by a sieve-like surface while it is exposed to a suction airstream.
Cleaning of fiber material is further intensified if it is aligned in parallel before being exposed to a suction airstream. In such case, increased relative movement between the clothing and fiber material to be cleaned becomes possible. As a result, not only is dust which is located anywhere on the surface of or loosened from the fibers sucked off, but dust also scraped off from the fibers carrying it, so that even such dust can be removed by means of the suction airstream.
On open-end spinning machines, fiber material may be fed to a clothing cylinder in the form of a sliver including fibers aligned in parallel. The clothing cylinder may be an opening cylinder.
According to one feature of the present process while fiber material is exposed to a suction airstream it is also retained in the form of a fiber tuft in the nip of the supply device. The scraping-off effect is thereby further intensified and results in thorough cleaning of the fiber material. This is extremely important in open-end spinning, since the composite fiber structure is interrupted during spinning, and any dirt impairs the spinning process considerably.
To prevent light-weight material, such as fly, etc., from sticking to the sieve-like surface and thus possibly impairing the operating ability of the dust-eliminating device, according to a further feature of this invention an air jet is briefly directed onto a side of the sieve-like surface which faces away from the fiber transport path. This ensures that such constituents are lifted from the sieve-like surface, so that the dust-eliminating device can perform its function perfectly. At the same time, the cleaning interval for the sieve-like surface can be coordinated with the work process of the textile machine or apparatus on which the invention is used in such a way that this work process is not impaired.
According to an aspect of this invention in carrying out the process, the sieve orifices of the sieve-like surface are inclined at an acute angle counter (i.e., opposite) to the fiber transport direction. This ensures that the suction airstream acting on the side of sieve-like surface which is away from the fiber transport path can indeed draw off the dust loosened from fibers, but with no possibility of larger particles (such as dirt or fibers) becoming stuck in the sieve orifices as a result.
One preferred embodiment includes the sieve orifices formed as elongate holes which extend essentially transversely relative to the fiber transport direction.
According to another advantageous feature of this invention, the sieve-like surface may be arranged in the peripheral region of a clothing cylinder. To ensure that the suction airstream exerts a centering effect on the fiber/airstream, the sieve orifices formed as elongate holes are arranged at an acute angle to the transport direction that, from the perspective of the fiber transport direction, has their ends inclined towards an imaginary central-peripheral line of the clothing cylinder. This also ensures that light-weight fly picked up by air flowing through the sieve-like surface is oriented in the direction of these sieve orifices formed as elongate holes and thus passes through such sieve orifices. This reduces danger of clogging the sieve-like surface.
With sheet metal sieves, sieve orifices are usually made by stamping. However, it is not possible in this way to orient the sieve orifices relative to the direction of movement of the fiber/airstream in a desired manner. Nevertheless, so that a suction airstream oriented in the desired way can be generated simply, according to another feature of this invention, lamella (i.e., thin scales or plates) are formed in the sheet metal by means of a combined deep-drawing/stamping tool. These lamellae separate the elongate holes from one another and are inclined opposite to the fiber transport path in the fiber transport direction. It is not necessary to stamp material out of the sheet metal to form the elongate holes; instead, the inclined lamella can be formed by making a cut parallel to the desired direction of each elongate hole with the resulting subsequent plastic deformation of the sheet metal in front of this cut in relation to the fiber transport direction.
To make it possible to occasionally remove fly constituents, which despite the inventive inclination of the sieve orifices nevertheless might settle on the sieve-like surface, a blowing-air nozzle is directed onto a side of the sieve-like surface facing away from the fiber transport path. A device for generating a brief compressed-air jet is operatively associated with the nozzle.
A feature of this invention also includes measuring the dust content in fiber material. For this purpose, in a further embodiment in accordance with the invention, a widening dust-collecting chamber, having several filters in succession of increasing fineness, is arranged between the sieve-like surface and the suction-air source. Since the filters or sieves through which the dust-laden air first passes are coarser than the following filters or sieves, the finer fly and dust constituents are allowed to pass through the first sieve or filter and are intercepted only at the next filter or one of the following filters, thus ensuring that different waste constituents are separated. To make it possible to separate different types of dust, while also determining the exact ratio of the individual proportions of dust, dirt and good-quality fiber, according to this invention a dust-eliminating orifice (with which a widening dust-collecting chamber is associated), a dirt-eliminating orifice (with which a dirt-collecting chamber is associated), and a fiber discharge orifice (with which a fiber-collecting chamber is associated) are arranged in succession along the fiber transport direction and in the wall surrounding the clothing cylinder.
This invention makes it possible to remove dust from fiber material on a wide variety of textile machines and thereby avoids the danger of clogging a sieve surface retaining fiber material opposite to the effect of a suction airstream. Dust-elimination conditions which remain unchanged even over relatively long periods of time are consequently achieved on preparatory machines and cards, etc. On open-end spinning machines, which are highly sensitive to the incidence of dust, when a sieve surface formed in accordance with this invention is arranged in a peripheral wall surrounding the opening cylinder, in the region of fiber material still retained as a fiber tuft by the supply device, not only is clogging of the sieve-like surface prevented, but over long operating periods dust deposits are avoided in the collecting groove or at the open edge of the spinning rotor, thereby preventing thread breakages.
The above description shows that the clothing cylinder, in the effective range of which the sieve-like surface is located, can have various emobidments. Depending on the type of machine to which the invention is applied, a saw-tooth or porcupine roller (for example, in the opening device of an open-end spinning installation or in the taker-in of a card) or even an impeller (for example, in spinning preparation) can be used as a clothing cylinder.